1. Field of the Invention
The present invention relates to a color image recording device for use in a color copying machine, a color facsimile, a color printer and the like and more particularly to a color image recording device which has a function to perform color edit processings including a color conversion processing, a coloring processing and the like.
2. Description of the Related Art
A conventional digital color copying machine comprises an image reading unit which scans an original document to read image data thereon, an image editing unit for processing and editing the image data, an image outputting unit for recording the processed and edited image data, and a control unit for controlling the image reading unit, image editing unit and image outputting unit. In the conventional digital color copying machine, the image data is subjected to a variety of editing processing in the image editing unit.
The schematic structure of the conventional digital color copying machine having the above-mentioned image editing function will be described with reference to an embodiment disclosed in Published Unexamined Japanese Patent Application No. 47988/1989.
In FIG. 21 which is a block diagram showing the structure of an image data processing system employed in the above-mentioned digital color copying machine, an IIT (Image Input Terminal) 100 separates an image of a color original document into B (blue), G (green) and R (red) that are three primary colors of light by use of a CCD line sensor to be converted into digital image data, respectively. An IOT (Image Output Terminal) 115 performs exposure by means of a laser beam, development by means of a toner, and fixing to thereby reproduce a color image. An END conversion circuit 101 - an IOT interface 110, which are respectively interposed between IIT 100 and IOT 115, constitute an image data editing and processing system (which is referred to as IPS; Image Processing System). In particular, the IPS converts the image data of the three primary colors, R, G, B, signals into toner color signals including Y (yellow), M (magenta), C (cyan) and further K (black or India ink) and, every developing cycle, outputs the toner color signal that corresponds to the developing color.
The IIT 100 reads 1 pixel with a predetermined density of, for example, 400 spi with respect to each of B, G, R by use of the CCD sensor, to output an output signal for each of the colors in the form of density data of 8 bits, that is, of 256 gradations.
The IPS inputs the density data of B, G, R from IIT 100 and, in order to enhance the reproducibility of the colors, reproducibility of the gradations, reproducibility of the fineness, the IPS performs various kinds of data processings to convert the toner color signals of develop process colors into on/off signals and then outputs the on/off signals to the IOT 115.
An END conversion (Equivalent Neutral Density Conversion) module 101 is used to adjust and convert the three primary color signals each of 8 bits into grey balanced color signals, and a color masking module 102 is used to perform a matrix operation on the B, G, R signals to thereby convert them into the toner color signals that correspond to the amounts of toners of Y, M, C. An original document size detect module 103 detects the size of an original document in a pre-scanning step and erases a platen color, that is, performs a frame erasing processing in an original document read scanning step. A color conversion module 104 converts a color specified in a specified area in accordance with an area signal which is input from an area image control module 111.
And, UCR (Under Color Removal) and Black Generation Module 105 generates a proper amount of K, which is enough to prevent a muddy color from occurring, to thereby reduce the amounts of Y, M, C by an equal amount respectively according to the amount of K generated. At the same time, the Module 105 gates the K signal and Y, M, C signals after the under colors thereof are respectively removed in accordance with the respective signals of a mono-color mode and a 4-color full color mode.
A space filter 106 is a non-linear digital filter which has a function to recover blurring and a function to remove moire. A TRC (Tone Reproduction Control) Module 107 operates to adjust the density, contrast, color balance and the like in order to enhance the reproducibility.
A reduction/extension processing module 108 performs a reduction/extension processing in a main scanning direction, while the reduction/extension processing in a sub-scanning direction can be performed by adjusting the scanning speed of the original document.
A screen generator 109 converts a process color gradation toner color signal to an on/off binary toner color signal and outputs the same. In particular, the binary toner color signal is output through an IOT interface module 110 to the IOT 115. And, an area image control module 111 includes an area generator circuit and a switch matrix. Also, an edit control module includes a plane memory 112, a color palette video switch circuit 113, a font buffer 114 and the like and the edit control module is used to perform a various kinds of edit control.
In the area image control module 111, seven (7) rectangular areas and the priorities thereof can be set in the area generator circuit, and area control information is set in the switch matrix in such a manner that it corresponds to the respective areas. The area control information includes modulation select information as to color conversion, color modes including a mono color mode or a full color mode, photograph, characters and the like, TRC select information, screen generator select information and other similar information. The control information is used to control the color masking module 102, color conversion module 104, UCR module 105, space filter 106 and TRC module 107. Here, it should be noted that the switch matrix can be set by means of software.
The edit control module is used to read images in a non-rectangular area including, for example, a circle graph and the like and to paint out or completely color a specified area having an unlimited shape with a specified color, that is, the edit control module is adapted to be able to perform a coloring processing. In the edit control module, an area command of 4 bits is written into 4 pieces of plane memories and an edit command in each of the areas of the original document is set in terms of 4 bits using 4 pieces of plane memories.
In the above-mentioned IPS, when the three primary color signals are converted to the toner color signals, there arise some problems as to the following cases: that is, how to adjust the color balance; how to reproduce the color to the ITT read characteristic and to the IOT output characteristic; how to adjust the density balance and contrast balance; how to adjust the excessively increased contrast or blurring in the edge and the moire; and so on.
In order to solve these problems, with the IPS, the 8-bit data representing the three primary color signals, B, G, R, respectively, which are obtained by reading the original document with the IIT 100, are respectively input to the END conversion module 101, in which the 8-bit data are at first END converted and are then converted (that is, color toner masked) to the toner color signals of Y, M, C. Then, the IPS performs the original document size detecting, frame erasing and color converting processing, which can be performed efficiently by means of the full color data, and then removes the under colors thereof and generates the India ink, thereby selecting a toner color signal X of a developing color. On the other hand, the space filter, color modulation, TRC, reduction/extension and other similar operations are processed by processing the data of the developing color to thereby reduce the amount of processing when compared with the processing by means of the full color data, in particular, to reduce the number of conversion tables used to a third of that of the full color data processing. Simultaneously, the kinds of processings are increased accordingly to thereby enhance the adjustment flexibility, color reproducibility, gradation reproducibility and fineness reproducibility.
In case of the full color (4-color full color) processings, the original document size information, edit area information and other kinds of original document information are firstly detected in the pre-scanning operation. Then, for example, each time a copy cycle to convert the toner color signal X of the developing color to Y and then a copy cycle to convert the toner color signal X of the developing color to M, C, K respectively are executed sequentially, a signal processing corresponding to 4 times of original document read scannings is performed.
In the above-mentioned conventional digital color copying machine, the color editing processings including the color conversion, coloring and the like are performed on the toner color signals. In this manner, in the conventional color image recording device, since the color edit processings are performed on the toner color signals, Y, M, C, K or the three primary color signals, B, G, R, there is a limit to the improvement in the accuracy of the color editing. In other words, for example, if it is assumed that the color editing is performed on the three primary colors and when a color conversion operation to convert a desired color in the original document to another desired color is performed, the color to be converted in the original document and the color obtained after such conversion are respectively set in the densities of B, G, R. However, it is not easy for not only an ordinary user but also a skilled person to represent one color by the three primary colors and, therefore, it is difficult to accomplish such a color editing processing as desired.
Also, the three primary colors or toner colors vary according to the kinds of the color image recording devices and are not standardized color specification systems. Therefore, for example, even if image data produced by means of computer graphics can be input into a color copying machine or the like, the image cannot be always output in a desired color.